A student produces a scale drawing of a pancreatic acinar cell observed under a transmission electron microscope (TEM).
Figure 1 shows the student's drawing of the acinar cell.
The actual maximum width of this pancreatic acinar cell is 25 μm25\ \mu\text{m}25 μm.
Calculate the actual diameter of the highlighted zymogen granule in micrometres (μm\mu\text{m}μm). Show your working.